This bug was originally marked as duplicate of bug 211962, that is already resolved. This bug is still valid, so this seems to be another bug, but it might be related.
Build: NetBeans IDE 7.3 (Build 201302132200)
VM: Java HotSpot(TM) Client VM, 23.7-b01, Java(TM) SE Runtime Environment, 1.7.0_17-b02
OS: Windows XP
Stacktrace:
java.lang.ClassNotFoundException: org.openide.util.actions.CallableSystemAction$1
at java.net.URLClassLoader$1.run(URLClassLoader.java:366)
at java.net.URLClassLoader$1.run(URLClassLoader.java:355)
at java.security.AccessController.doPrivileged(AccessController.java:0)
at java.net.URLClassLoader.findClass(URLClassLoader.java:354)
at java.lang.ClassLoader.loadClass(ClassLoader.java:423)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:308)